1. Field of the Invention
The present invention relates to a connector terminal having, at a pressure contact portion connected to an electrical wire, characteristics such that a contact resistance is small and the connection is stable even at a high temperature.
2. Prior Art
In general, a connector terminal used for connecting an automotive wire harness or the like is made of a base plate that has an electrical contact portion at its front side and an electrical wire connecting portion at its rear side. A conductor of an electrical wire and an insulating coating thereon are pressed by a pair of wire barrels and a pair of insulator barrels each extending upwardly from both edges of the base plate, respectively. Methods for connecting the connector terminal and the electrical wire, such as a W-shape contact pressure method, a C-shape contact pressure method, an F-shape contact pressure method, a soldering method and the like are widely used for mass production.
The contact resistance and the electrical wire fixing force are representative of basic characteristics which show the quality of the connection according to the F-shape contact pressure method. These values are changed in accordance with the cross-sectional shape of the connection. The cross-sectional shape of the connection may be represented by a crimp height (CH) and a crimp width (CW) during the pressing operation. Although it is preferable to set the crimp height CH in a stable region of the contact resistance, it is necessary to take into consideration the strength of a neck portion of the terminal and a breakdown due to vibrations. On the other hand, in an electrical wire fixing force curve, if the crimp height CH is greater than its maximum value, the electrical wire will be pulled apart from the terminal, whereas if the crimp height CH is smaller than the maximum value, the electrical wire will be broken down.
In view of the above-described phenomenon, according to the F-shape connecting method for the conventional connector, a CH CW ratio represented by the following equation has long been selected to be about 40%. ##EQU2##
From various experiments and studies, it has been found that the F-shaped contact pressure method suffers from the disadvantage that the contact resistance of the contact pressure portion is increased in the high temperature atmosphere.